The usual construction of rotary pressure leaf filters employs a perforated outlet manifold on which a plurality of circular filter leaves are stacked with the hub portions being forced together by means of a nut threaded on the distal end of the manifold. In order to prevent spurious leakage into the outlet manifold between the interfaces of the hubs, o-ring sealing gaskets have been positioned in facial grooves in the hubs and held in compression as the hubs are forced together on the outlet manifold. Relatively frequent replacement of the o-rings have been required to prevent the unfiltered liquid from leaking past these rings into the manifold.
For many applications, the faces of the filter leaves are covered with a cloth fabric which is sealed to the hub by means of a ring type clamp which compresses the fabric against an annular rubber gasket disposed on the circumferential surface of the hub. I have found this construction to be unsatisfactory for some applications because the gasket when hot is readily deformed by the pressure differential across it whereby it is forced into the drainage member where it interferes with the flow of filtered liquid through the drainage member into the manifold. Moreover, this flow of the gasket material can result in leakage between the fabric and the gasket.
There are a large number of filter leaves of this type in use and the cost of replacement would be extremely great. Therefor, it would be desirable to provide a way to modify the existing filter leaves to avoid the two major problems discussed above. Moreover, it would be desirable to provide a new and improved filter leaf construction which eliminates these heretofore mentioned problems.